Scientists are developing a new generation of dextrous mini-robots for use in minimally invasive surgery.

New Scientist magazine reports that several prototypes of the radio-controlled robots are being tested in animal models.

They have been used to help perform gall bladder and prostate removal in pig experiments.

The University of Nebraska team believe they could potentially revolutionise minimally invasive keyhole surgery.

These robots will some day replace standard surgery

Dr Dmitry Oleynikov

There are several prototypes of the robots, each about 15 millimetres in diameter.

One has a camera attached, another is equipped with a needle that can extract a small piece of tissue for a biopsy.

The robot that moves around the abdominal cavity has a spiral pattern on its wheels, allowing it to transverse multiple organ surfaces and move around without slipping or damaging tissue.

Easier surgery

Dr Dmitry Oleynikov, who invented the robots, believes they could make keyhole - or laparoscopic - surgery easier, and better for the patient, by requiring smaller, and perhaps fewer incisions.

And because the robots are so small and dextrous they give the surgeon a much broader visual field, unlike traditional laparoscopic cameras that are limited by freedom of movement.

In tests on a live pig, the robots were were inserted through the animal's mouth, and once inside the stomach, surgeons cut a small hole in the stomach wall, which allowed the robot access to the whole abdominal cavity.

In the future, a surgeon removing a gall bladder or performing a liver biopsy may be able to introduce the robots via the patient's mouth, then pass them through a small incision in the stomach wall.

Dr Oleynikov said: "These robots will some day replace standard surgery, and at some point the surgeon's hands won't have to be in the body at all."

He also hopes that in future the tiny machines may also play a big role in emergency medicine.

Newer versions are being developed to stop internal bleeding by clamping, clotting or cauterizing internal wounds.

Concerns

Mr Christopher Eden, a consultant urologist at the North Hampshire Hospital in Basingstoke, told the BBC News website that a move to greater use of robots in surgery seemed inevitable.

However, he was concerned that the equipment was expensive, and would divert money away from training doctors how to carry out laparoscopic procedures.

He said keyhole surgery could be used to carry out complex surgery, such as prostate removal, but required lengthy and intensive training.

"My concern with robotics is that you are putting surgeons in a position where they are completely reliant on machines which are expensive, can wear out, and become obsolete," he said.

"There is some scepticism in the UK about the idea that robot surgery is the best thing since sliced bread."